Such a length adjustment is known from DE 1 081 286 B. To ensure a predetermined mutual angle position of the two rotary elements to each other during the assembly of the rotary elements, at an end of the first rotary element an insert is mounted, which engages with a projection in a spline groove of the longitudinal toothing, which is formed as a splined shaft toothing. A longitudinal tooth of the second rotary element is removed. During the assembly of the two rotary elements in one another, i.e. during the axial inserting of the two longitudinal toothings into one another, no longitudinal tooth of the second rotary element can be inserted into the spline groove with the insert. Only in the one angle position, in which the splined groove with the insert and the removed tooth of the second rotary element are arranged at the same angle to each other, the rotary elements can be connected to each other or can be inserted into one another. The insert is in this case formed as a spring wire clamp which is formed U-like and has two parallel projections, which are connected to each other via an intermediate piece. One of the parallel projections engages in the spline groove. The other parallel projection is inserted into a central bore of the first rotary element, which is formed as a journal.
It is disadvantageous that a separate component, which is easily removable and thus easy to loose, is provided, which furthermore, represents a significant additional mass, which leads to imbalances.